Troyes won promotion to Ligue 1 by successfully defending a first-leg lead in their relegation playoff with Lorient.
Leading 2-1 thanks to an injury-time winner from 40-year-old midfielder Benjamin Nivet in Thursday's first meeting, the second-tier side stood firm to secure a goalless draw at Stade du Moustoir and ensure they will swap divisions with their hosts next season.
It could have been a different outcome had a bullet header from Lorient's Cameroon international forward Benjamin Moukandjo not come back off the right-hand post with four minutes played.
The visitors' early let off suggested they could have been in for a long night but the home side struggled to create clear chances as they attempted to overturn the slender deficit.
Walid Mesloub and former Portsmouth man Arnold Mvuemba were both off target from distance for Lorient, while Thiago Xavier could have put the result beyond doubt with a late header at the other end.